1. Field of the Invention
The present invention relates to an ink-jet ink composition and, more particularly, to an ink-jet ink composition suitable for thermal ink-jet printing.
2. Description of Related Art
Currently, ink-jet printing achieved by ejecting ink to a printing medium through a printhead in accordance with a piezoelectric type or thermal ink jet type is well known. The piezoelectric type is applied by supplying a voltage to the piezoelectric material which can expand and shrink so as to generate a jetting spray. The thermal ink jet type is utilized by heating and vaporizing ink to form bubbles and jetting onto a printing medium.
For the thermal ink jet type, there exist some shortcomings such as whisks and satellites, which always retard the resolution and other characteristics of an image. Satellites are the undesired small dots that form around the main droplet at the instance of jetting. Furthermore, when too many satellites are formed, blots will be observed. This has a serious impact on printing quality, since the image will become unclear and blurry.
In order to overcome the above disadvantages, U.S. Pat. No. 4,794,411 discloses a modified printhead by shifting the resistor below the orifice. U.S. Pat. No. 5,992,968 also provides a method of reducing the returning speed of the printhead after printing. Such design may shorten the distance between the satellites and the main droplet, but can""t eliminate these satellites.
Therefore, it is desirable to improve the printing quality in different ways, for example, providing an alternative ink-jet ink composition, to mitigate and/or obviate the aforementioned problems.
The object of the present invention is to provide an ink-jet ink composition which can decrease satellites, avoid blots, and improve image quality when applying on a printing medium.
To achieve the object, the ink-jet ink composition of the present invention includes (a) at least one water-soluble dye; (b) at least one low vapor-pressure solvent; (c) a nonionic non-amphoteric surfactant; (d) a fluoric surfactant; and (e) the balance water. The ink-jet ink composition of the present invention is suitable for thermal ink-jet printing.
Other objects, advantages, and novel features of the invention will become more apparent from the following detailed description.
The ink-jet ink composition of the present invention includes (a) at least one water-soluble dye; (b) at least one low vapor-pressure solvent; (c) a nonionic non-amphoteric surfactant; (d) a fluoric surfactant; and (e) the balance water. Additionally, the ink-jet ink composition of the present invention can further include (f) at least one additive.
The water-soluble dye used in the ink-jet ink composition of the present invention can be selected from the group consisting of C.I. Acid Blue 9, C.I. Acid Red 18, C.I. Acid Red 27, C.I. Acid Red 2, C.I. Acid Yellow 23, C.I. Direct Blue 199, C.I. Direct Violet 99, C.I. Direct Yellow 86, C.I. Reactive Red 180, C.I. Reactive Red 159, C.I. Reactive Black 31 and Black-sp. The above water-soluble dyes can be used solely or by mixing with each other or with alkaline or ammonium compounds thereof. The concentration of the water-soluble dye is preferred between 0.1 and 10 wt %.
The low vapor-pressure solvent used in the ink-jet ink composition of the present invention can be selected from the group consisting of glycols such as ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, polyethylene glycol, polypropylene glycol, and derivatives thereof; diols such as butanediol, pentanediol, hexanediol, and homologous diols; glycol esters such as propylene glycol laurate; mono and diglycol ethers such as cellosolves, including ethylene glycol monobutyl ether, diethylene glycol ethers such as the carbitols, diethylene glycol mono ethyl, butyl, hexyl ethers, propylene glycol ether, dipropylene glycol ether, and triethylene glycol ether; long chain alcohols such as butyl alcohol, pentyl alcohol, and homologous alcohols; and other solvents such as sulfolane, esters, ketones, lactones such as .gamma.-butyro-lactone, lactams such as N-pyrrolidone and N-(2-hydroxyethyl)pyrrolidone, and glycerols and their derivatives.
The concentration of the low vapor-pressure solvent is preferred between 0 to 20 wt %.
An example of the nonionic non-amphoteric surfactant used in the present invention is acetylene glycol of formula (I), such as SURFYNOL 465 or SURFYNOL 104 supplied by Air Products and Chemicals, Inc. 
wherein the sum of n and m is an integer between 0 and 50, preferably between 0 and 20.
An example of the fluoric surfactant used in the present invention is fluoroaliphatic polymeric esters, including FC-430, FC-431, FC-740 supplied by 3M Co.
The weight ratio of the nonionic non-amphoteric surfactant to the fluoric surfactant is preferred between 1:1 and 1000:1, preferably between 30:1 and 800:1. The concentration of the nonionic non-amphoteric surfactant can range from 0.1 to 3 wt %, and that of the fluoric surfactant can range from 0.001 to 0.005 wt %.
In the present invention, the ink-jet ink composition can optionally include other additives such as microbial reagents. For example, NUOSEPT (supplied by Nudex, Inc., a division of Huls Americal), UCARCIDE (supplied by Union Carbide), VANCIDE (supplied by RT Vanderbilt Co.) and PROXEL (supplied by ICI Americas). The concentration of the microbial reagents can range from 0.1 to 0.5 wt %.
Additionally, water is used to balance the ink-jet ink composition in the present invention.
The following examples and comparative examples are used to further describe the present invention. However, the scope of the present invention will not be limited by such examples.